The present invention relates generally to a substrate transfer apparatus for transferring substrates such as semiconductor wafers, and more particularly, to a substrate transfer apparatus for transferring substrates in order to load/unload substrates onto/from a predetermined position in a processing chamber for conducting processing such as etching and the like on substrates in the manufacturing process of semiconductor elements such as integrated circuits.
Semiconductor wafers are thin disks usually made of silicon and the like, and on the semiconductor wafers, desired integral circuits are made by utilizing dry etching, chemical vapor deposition, hereinafter CVD, and other processing techniques. Since the interior of the wafer processing chamber is required to be maintained usually at a vacuum or with a strictly controlled atmosphere containing gas, the processing chamber is of an airtight structure and the space therein is confined. For this reason, the apparatus transferring semiconductor wafers within the processing chamber is required to be as compact as possible. Furthermore, the semiconductor transferring apparatus is also required to generate as little dust, friction powder, etc., as possible so that foreign materials will not adhere to semiconductor wafers or impurities will not be mixed into the thin film formed on the surface thereof.
The conventional semiconductor wafer transfer apparatus is arranged so that a semiconductor wafer holding member is provided on the tip end of a transfer arm having a plurality of joints and the holding member is moved by bending the joints. Concretely, there are transfer apparatuses having such structures as disclosed in the Japanese Laid-open Patent Publication Nos. 1-157547 and 1-183383.
However, since the conventional semiconductor transfer apparatus has only one transfer arm provided in the processing equipment, it has a drawback that the transfer operation takes time and thus the entire processing time becomes long.
Namely, the usual processing equipment has a plurality of reaction chambers or processing chambers, and transfers semiconductor wafers sequentially to respective processing chambers so as to conduct respective processing steps in respective chambers. With one transfer arm, however, it is necessary to repeat an operation in which, for example, after taking out a semiconductor wafer from the final processing chamber, the transfer arm is returned to the previous processing chamber to the final processing chamber so as to take out another semiconductor wafer from the previous processing chamber, the arm is moved to the final processing chamber to transfer the semiconductor thereto, and the arm is again returned to the processing chamber before the previous processing chamber. Therefore, a troublesome and time-consuming operation in which semiconductor wafers are transferred one by one by reciprocating the transfer arm many times to respective processing chambers, has been conducted conventionally.
Accordingly, an essential object of the present invention is to provide a substrate transfer apparatus which is capable of efficiently conducting a transfer operation for substrates such as semiconductor wafers or the like within the processing equipment without reciprocatingly moving the transfer arms many times.